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The present invention relates to a body for a dump vehicle such as a dump truck, dump trailer, or dump semi-trailer that dumps from an end of the dump body.
Dump vehicles are used in numerous applications for moving material from one location and depositing it in another. Dump vehicles include dump trucks, dump trailers, and semi-trucks with dump trailers and similar dump systems. Dump trailers are trailers that are made to be placed on a dumping mechanism or have a dumping mechanism built into the trailer. In one example, a dump truck pulls a dump trailer, both with loads. The dump truck drops the trailer, dumps the first load, and then the dump trailer, which fits inside the first dump body (commonly known as a xe2x80x9ctransferxe2x80x9d dump), is pulled, pushed, or otherwise loaded into the first dump bed and the second load is dumped. An example of such a system is discussed in U.S. Pat. No. 5,219,260 by Smith et al. entitled APPARATUS FOR TRANSFERRING A TRAILER BODY BETWEEN A TRAILER AND TRUCK BODY, issued Jun. 15, 1993.
A dumping semi-truck (which will be referred to as a xe2x80x9csemi-dumpxe2x80x9d for convenience of discussion) has a tractor pulling a trailer that has a dump mechanism. The tractor-trailer semi-dump generally can haul larger, heavier loads than a dump truck. Furthermore, the trailer can be dropped and the tractor used for other purposes. Trailers used in semi-truck rigs typically have a rear set of wheels, with the forward portion of the trailer being supported by a pivoting disk that transfers a portion of the weight to be distributed between the front and rear wheels of the tractor. A set of jack supports, or legs, can be dropped at the front end of the trailer to support it and allow the tractor to de-couple from the trailer. In a standard trailer, or wagon, the trailer has both a front and rear set of wheels, and is pulled by a tongue that may or may not support some of the trailer weight. Usually the tongue is a beam or rigid yoke that provides strength in the direction of pull.
Dump bodies, whether on a truck, trailer, or semi-trailer, have taken many shapes, often to address specific applications. For example, dump trucks have been designed for use in open-pit mining operations that have a large capacity that facilitates rapid loading of fractured rock and dirt or ore from a bucket of a power shovel or similar source. They often dump into an accumulation pile or overburden pile.
Other dumps are done while the dump vehicle is moving. These so-called xe2x80x9crolling dumpsxe2x80x9d allow the material carried in the dump body to be advantageously spread or pre-spread over the job site. For example, a dump truck carrying road base can initiate dumping while moving forward and distribute the road base along the planned route. It is often similarly desirable to spread loads when delivering landscaping materials, arena footing, and even simple fill.
A spreader gate is often added to the back of a dump body to promote even distribution of the material delivered in a rolling dump. The spreader gate is generally a panel covering the back end of the dump body. One simple version of a spreader gate is simply hinged at the top. The bottom of the gate is released before dumping is startled, and the gate, while being free to swing open from the bottom, provides some transverse spreading of the material as it is dumped. Another version is lifted a selected amount to create an opening at the bottom end of the dump body. Other versions use mechanical devices, such as hydraulic cylinders and pistons, to swing or lift the spreader gate a selected amount. These devices allow the operator to open the spreader gate from the cab, i.e. without having to stop the dump vehicle, and to adjust the amount the spreader gate is open during the dump operation.
However, even with a spreader gate some mounding of the material can occur, particularly with a half-pipe dump body. A half-pipe dump body has basically a semi-circular or semi-ellipse cross-section, with or without sidewall extensions. Half-pipe dump bodies have found wide acceptance because of the strength, capacity, simplicity of manufacture, and lightweight that they provide compared to a rectangular dump box, for example. An example of a dump truck with a shell in the form of a half ellipse is shown in U.S. Pat. No. 3,844,616 by Acker, entitled DUMP TRUCK HAVING AN OPEN SHELL IN THE SHAPE OF ONE-HALF OF AN ELLIPSE, issued Oct. 29, 1974.
Another example of a dump bed in the form of an ellipse is sold under the name SUPERDUMPS(trademark) by STRONG INDUSTRIES. The bed is tapered so that the sides widen toward the rear of the bed, and the radii of the ellipse also increase toward the rear. However, the curved rear edge of the dump bed can result in center mounding during a rolling dump.
In a rectangular dump box, the side load on the walls of the dump box can cause bowing. The walls are typically reinforced to avoid bowing, but this adds material cost and weight to the dump box and diminishes the weight of the load that can be carried by the vehicle on public roads because the maximum load is usually the gross weight minus the vehicle weight. While the rectangular dump box provides good material distribution in a rolling dump, material, especially viscous or sticky material such as wet sand or asphalt, can adhere to the corners of the dump box, especially the upper corners. Removing this material from the upper corners can be time consuming and frustrating for the driver or site crew, and can cause a separate mound of material at the end of the rolling dump.
Therefore, a dump body that provides more even dumping while reducing material adhesion during dumping is desirable.
A dump vehicle body transitions from a tubular front end to a rectangular rear, or dump, end. The tubular front end has curved section with a radius of at least 20% of the body width to avoid material sticking in the upper region of the dump body during dumping. The dump end has a flat floor that reduces forming a mound of material in the center of the dumped load, which is particularly desirable during rolling dumps. The flat floor is particularly desirable when used in conjunction with a spreader gate. The flat floor extends at least 85% of the width between the walls of the dump vehicle body at the dump end.
In a particular embodiment, two sideportions are formed that transition from the curved section in front to L-shaped sections in the rear. The sidepieces are bent from a sheet of metal to form both the walls and the floor of the dump body. In a further embodiment, a floor piece is welded between the horizontal portions of the sidepieces (or tangentially to the curves). In another embodiment, the sideportions are formed to have a curve describing an arc of about 90 degrees with increasing radius from the dump end to the front end of the dump body. A flat floor portion extends between the sideportions, and in a particular embodiment is trapezoidal. In some instances, the dump body is rectangular when viewed from the top, in others it is trapezoidal or other shape(s).